The present invention relates to a north seeking and course keeping gyro device, of the type including a gyro presenting two measuring axes and having its spin axis oriented essentially vertically, the gyro being supported by a procession gimbal.
Devices of this type further include two position sensors operative to determine the inclination of this gimbal in two directions which are perpendicular to one another and to the gyro spin axis, one of these directions being parallel to the gimbal precession axis. The gyro device additionally includes a further gimbal, in which the precession gimbal is mounted and which itself is mounted in a housing via an axis which is perpendicular to the precession axis. A moment generator, which acts on the axis of the further gimbal, is actuated by a first position sensor and includes a computer circuit for calculating the north deviation .alpha. with respect to a reference direction from the signals generated by means of the gyro.
German Auslegeschrift [Published Application] No. 2,741,274 discloses such a gyro device. This is a dual-axis gyro with essentially horizontally disposed input axes, the position sensors of the axes acting in a crisscross manner on torque generators disposed on both axes. The voltages applied to the torque generators are simultaneously transmitted to a north deviation computer to calculate the north deviation.
In this arrangement it is necessary to set both input axes to the horizontal orientation before the start of the north determination process.
The same prior art also discloses a gyro device which can, in addition to effecting the north determination, be used to determine a course, i.e. as a gyrocompass. For this purpose, the housing of the gyro is pivoted by 90.degree. about one of the input axes. The spin axis then has an essentially horizontal orientation. The gyro is fixed in this position and measures the angular velocities about the input axes fixed to the vehicle, there additionally being provided accelerometers which sense the position of the vehicle with respect to the horizontal.
This gyro device has a complicated structure for course determination, particularly because of the use of accelerometers which must meet very high accuracy requirements. Moreover, evaluation for the course determination is complicated.